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Tcarpenter · 02-07-2022, **(Subject: Isx 2350 )**

Looking for some help and guidance. Truck is a 2015 international lonestar that's been permanently fixed for well over 400k. Shop south of atlanta did the fix. With in the last 8k miles, the truck with fluctuate idling. Does matter if it's set on high idle or not. By insite truck is set to low idle at 700 rpm. It will start then when I first start the truck but by time it builds air it'll be at 900 for a few seconds then drop down to 800 and go back up. Even if I do highnidle it'll bounce around a couple hundred rpms.

I've done injector performance test which it passes. Looking at fuel pressure on data logger it'll command 10878 and the measured will bounce around from 10780 up to 10943. I'm kinda at a lost, I have no codes what so ever. Not real sure where to start at and not wanting to piss money away.

Rawze · 02-08-2022, **(Subject: Isx 2350 )**

First of all, who did the de-mandate?.

next, is to check to see if it passes a fuel rail leak test.
ref:

Then also, when was the last time the guts in the fuel pump replaced (tappets, rollers, plungers, etc.)?.

Tcarpenter · 02-08-2022, **(Subject: Isx 2350 )**

(02-08-2022 )Rawze Wrote: First of all, who did the de-mandate?.

next, is to check to see if it passes a fuel rail leak test.
ref:

Then also, when was the last time the guts in the fuel pump replaced (tappets, rollers, plungers, etc.)?.

Was worked on by Haggai roughly 4 years ago. I don't remember the guys name that came out and did the tuning then. But regardless truck hasn't been touched program wise since then.

It passes the leak down test, did it twice. First time it lost 1843 and the second time it lost 1945.

Honestly it's been awhile since I've opened up the fuel pump and changed things out. I'm assuming that's what your going to reccommend for me to start at.

Rawze · 02-08-2022, **(Subject: Isx 2350 )**

Fluctuating rpm is usually fuel leaking into a cylinder is why I asked if it would pass a rail leak test. Could be other things as well.

If you disconnect the intake piping from the CAC, then idle it, does it stop the problem?.

Also, if it was done 4 years ago, you will want to get a program update at some point in the near future too. A lot has changed since then. Pulling a copy of the program out of it and e-mailing it to me, I can inspect and update it.

Tcarpenter · 02-09-2022, **(Subject: Isx 2350 )**

(02-08-2022 )Rawze Wrote: Fluctuating rpm is usually fuel leaking into a cylinder is why I asked if it would pass a rail leak test. Could be other things as well.

If you disconnect the intake piping from the CAC, then idle it, does it stop the problem?.

Also, if it was done 4 years ago, you will want to get a program update at some point in the near future too. A lot has changed since then. Pulling a copy of the program out of it and e-mailing it to me, I can inspect and update it.

I'll have to check and see if disconnecting the intake piping makes it stop or not and get back to you. Same on pulling a copy of the tune. It'll be this weekend before I'm back around that truck. Appreciate the guidance Rawze.

Tcarpenter · 02-10-2022, **(Subject: Isx 2350 )**

(02-08-2022 )Rawze Wrote: Fluctuating rpm is usually fuel leaking into a cylinder is why I asked if it would pass a rail leak test. Could be other things as well.

If you disconnect the intake piping from the CAC, then idle it, does it stop the problem?.

Also, if it was done 4 years ago, you will want to get a program update at some point in the near future too. A lot has changed since then. Pulling a copy of the program out of it and e-mailing it to me, I can inspect and update it.

Pulled the piping apart from intake this evening and it didn't make a difference. Next thought?

Rawze · 02-11-2022, **(Subject: Isx 2350 )**

(02-10-2022 )Tcarpenter Wrote:
(02-08-2022 )Rawze Wrote: Fluctuating rpm is usually fuel leaking into a cylinder is why I asked if it would pass a rail leak test. Could be other things as well.

If you disconnect the intake piping from the CAC, then idle it, does it stop the problem?.

Also, if it was done 4 years ago, you will want to get a program update at some point in the near future too. A lot has changed since then. Pulling a copy of the program out of it and e-mailing it to me, I can inspect and update it.
Pulled the piping apart from intake this evening and it didn't make a difference. Next thought?

Well that at least eliminates the turbo or an air related problem as the issue.

sounds like it is fuel related then.